低轨卫星紧组合导航UKF方法

UKF for Tightly Coupled Integration in LEO

摘要:

针对紧组合导航系统状态方程及量测方程的非线性,以低轨卫星为应用对象开展了无迹卡尔曼滤波UKF方法研究．给出了惯性系下的系统模型及算法模型,其中姿态直接采用修正Rodrigues参数来表述以避免四元数归一化条件的限制,系统状态更新采用四阶Runge-Kutta法以适应卫星的高速运动;之后通过数学仿真与广义卡尔曼滤波EKF进行了比较分析．结果表明:UKF滤波对于姿态精度明显优于EKF,提高了一个数量级,对于速度、位置精度两者滤波效果相当,但对于运算时间UKF耗时较长．因此实际应用中可根据导航精度与运算时间需求决定是否采用UKF方法．

Abstract:

Abstract: For the nonlinearity of the system dynamic and measurement model in Tightly Coupled Integration of LEO, this article holds research on Unscented Kalman Filter (UKF). The system model and UKF method in inertial frame are introduced. The attitude is represented by modified Rodrigues parameters instead of quaternion for its unit norm constraint, and the state is predicated by the fourth Runge-Kutta technique for satellite's high speed. The performance of UKF is compared to Extended Kalman Filter (EKF) by simulations. The results indicate that UKF is better on attitude precision than EKF by one order of magnitude, equal on position and velocity precision, but higher on computation time.